Numbers
one of 2 species in this genus in North America listed at
nearctica.comIdentification
Adult Female: covering brownish-gray, shaped like an oyster shell, broadly rounded posteriorly, tapering to a point anteriorly, with oval prosomal plate; body (only visible with covering removed) yellow, sac-like, pear-shaped, with 5 abdominal segments but no appendages or eyes
Adult Male: covering white, oblong or elongate, with middorsal and two lateral ridges; head yellowish-brown; body (only visible with covering removed) pale orange with wings
Nymph (Crawler): pale yellow to orange with no covering
Range
many areas of the world
in North America, mainly eastern United States and southeastern Canada, but liable to occur anywhere via shipments of cultivated and ornamental plants
Habitat
on leaves and stems of hostplant
Food
nymphs and adults feed mainly on leaves of Euonymus species;
other hosts include boxwood (Buxus), Bittersweet (Celastrus scandens), English Ivy (Hedera helix), holly (Ilex), privet (Ligustrum), honeysuckle (Lonicera), Paxistima canbyi, and Pachysandra terminalis
Life Cycle
overwinters as a fertilized female; one generation per year in the north, to three or four in the south; in early spring, eggs are laid underneath the protective scale, and hatch in May and June; crawlers migrate to leaves to feed; they may also be blown by the wind to other susceptible hostplants
Remarks
U. euonymi is the most common and most serious pest found on Euonymus plants.
See Also
males and females of
Unaspis citri are very similar (
1,
2,
3) but their main host is
Citrus, and they primarily attack the trunk and larger limbs; other hosts of
U. citri include
Annona muricata, Musa paradisiaca, Cocos nucifera, Psidium guajava, Ananas comosus, Artocarpus heterophyllus, Tillandsia usneoides
among other scale hosts on
Euonymus,
California Red Scale (
Aonidiella aurantii) is reddish and circular, and
Latania Scale (
Hemiberlesia lataniae) is light brown and oval
Internet References
live adult image of male and female
U. euonymi on host plant (U. of California at Davis)
photo of female (North Carolina State U.)
11 photos of various life stages and hostplant damage (zipcodezoo.com)
drawings and overview of
U. euonymi (North Carolina State U.)
drawings of adult female and male U. citri (Commonwealth Scientific and Industrial Research Organisation, Australia)
hostplants of scale insects in California with photos and overview of several specis (U. of California at Davis)
description, hostplants, control (Ontario Ministry of Agriculture and Food)
diagnosis of genus; PDF doc with detailed description of microscopic anatomy (European and Mediterranean Plant Protection Organization)
Contributed by
Robin McLeod on 29 January, 2007 - 6:36am
Additional contributions by
Chuck EntzLast updated 2 October, 2010 - 8:32am
